1. Field of the Invention
The present invention relates to the exchange of operating modules on coordinate positioning machines, such as machine tools or coordinate measuring machines. Such machines comprise an arm and a table, movable relative to each other, typically with three linear degrees of freedom. In use, an operating module, such as a cutting tool or a touch probe, for example, may be mounted to the arm of the machine to enable the machine to perform a cutting or measuring operation upon a workpiece which is supported on the table.
During operation of such a machine, it is frequently desirable to exchange one operating module for another. For example, in the case of a machine tool, after performing a cutting operation upon a workpiece, it may be desirable to exchange the cutting tool for a touch trigger probe, which will allow the machine to inspect the relative position and/or dimensions of the surfaces of the workpiece recently machined. In the case of a coordinate measuring machine, it may be desirable to exchange a touch trigger probe for an analogue probe, or a temperature sensing probe, for example. Alternatively, it may be desirable to exchange one stylus on a particular touch trigger or analogue probe, for another.
2. Description of Related Art
Systems providing the automatic exchange of operating modules on coordinate measuring machines are known for example from EP 293036, U.S. Pat. No. 4,637,119, EP 566719, U.S. Pat. No. 4,349,946 and WO89/05210. The prior art references disclose systems for exchanging operating modules in which the coupling and decoupling of an operating module to a retaining module supported on the arm of the machine is performed in a number of ways.